staging: comedi: ni_660x: tidy up ni_660x_read_register()

Rename this function to help shorten some of the long lines.

Remove the inline, let the compiler figure it out.

Change the 'unsigned' parameters to 'unsigned int' to fix the
checkpatch.pl issues:

WARNING: Prefer 'unsigned int' to bare use of 'unsigned'

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>